UNIVERSITY  OF  CALIFORNIA. 

AGRICULTURAL  EXPERIMENT  STATION. 
BERKELEY,  CAL. 


E.  W.  HILGARD,  Director.  BULLETIN  No.   117. 


THE  CONTROL  OF  THE  TEMPERATURE 
IN  WINE  FERMENTATION. 


JULY,   1897. 


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The  Control  of  the  Temperature 

in  Wine  Fermentation. 


By  A.   P.   Haynk. 


The  Control  of the  Temperature.  The  fermentation  of  wine  must,  or  the 
juice  of  the  grape,  results  in  the  main  in  the  splitting  up  of  the  sugar  it 
contains  into  almost  equal  parts  of  alcohol  and  carbonic  acid  gas.  While 
there  are  other  products  of  fermentation,  it  is  not  essential  for  our  immedi- 
ate purpose  to  dwell  on  them  in  this  connection.  The  transformation  of 
sugar  into  carbonic  acid  gas  and  alcohol  is  a  chemical  action  caused  by 
minute  plants  or  ferments  called  yeast.  It  is  well  known  that  all  chemical 
changes  of  this  sort  prodiice  heat ;  and  thus  it  will  be  seen  that  the  temper- 
ature of  a  fermenting  mass  of  a  sugar  solution  (grape  juice),  while  it 
depends  to  a  certain  extent  upon  the  outside  temperature,  is  chiefly  depend- 
ent upon  the  amount  of  heat  generated  within  the  tank  itself.  The  amount 
of  heat,  then,  that  is  produced  in  a  fermenting-tank  depends  upon,  first, 
the  percent  of  sugar  in  the  must  and  the  quantity  of  must ;  second,  the 
facilities  offered  by  the  tank  and  air  for  carrying  off  the  heat  generated  by 
fermentation,  or  conductivity  of  the  tank-walls,  the  amount  of  surface  ex- 
posed to  the  air,  the  circulation  of  the  must  within  the  tank,  etc.  ;  third, 
the  activity  of  the  yeast  cells,  i.  e.  the  rapidity  of  fermentation. 

Percentage  of  Sugar .  The  amount  of  sugar  in  the  must  varies  from  year 
to  year  in  the  same  place  with  the  same  varieties.  In  hot  countries  there 
is,  other  things  being  equal,  more  sugar  in  the  must  than  in  cold  countries. 
Some  varieties  of  grapes  give  more  sugar  than  others ;  and  as  high 
alcoholic  strength  is,  unfortunately,  paid  for  as  such  by  the  merchant, 
grape  growers  are  apt  to  select  those  varieties  that  produce  the  most  sugar, 
and  hence  alcohol  in  the  wine,  regardless  of  true  quality.  While  this  may 
be  proper  enough  in  cold  climates,  it  works  great  injury  to  the  general 
reputation  of  the  wines  of  warmer  countries,  for  alcohol  is  not  the  only 
desideratum  in  wine.  In  hot  climates  there  is  almost  always,  with  the 
excess  of  sugar,  a  correspondingly  smaller  amount  of  acid.  It  is,  however, 
important  to  note  that  very  high  sugar  contents  of  must  and  low  acid  gen- 
erally go  together,  and  that  they  both  are,  as  a  rule,  undesirable. 

Excess  of  Heat.  The  amount  of  heat  generated  within  the  fermenting- 
tank  is  very  great,  being  sufficient,  theoretically,  to  raise  above  boiling 
point  the  whole  of  a  must  rich  in  sugar.  Practically,  however,  the  heat  is 
generated  gradually  ;  and  much  of  it  is  carried  off  by  the  gas  generated, 
as  well  as  through  the  walls  of  the  vat,  and  from  the  surface  of  the  fer- 
menting liquid  ;  otherwise  fermentation  be}7ond  a  certain  point  would  be 
impossible.  This  fact  has  taught  wine-makers  in  warm  countries  the 
necessity  of  a  free  circulation  of  air  in  the  fermen ting-room,  unless  that 
air  is  hotter  than  the  temperature  of  the  fermenting  mass.  Hence  the 
benefit  of  the  practice  of  fermenting  in  small  packages  with  thin  walls : 
first,  because  of  less  actual  amount  or  quantity  of  heat  (calories)  gener- 
ated ;  and,  second,  because  of  the  facility  with  which  this  heat  can  be  car- 
ried off  and  thus  the  equilibrium  between  the  temperature  of  the  ferment- 


ing  mass  and  the  outside  air  be  maintained.  This  has  led  many  wine- 
makers  to  have  their  tanks  made  of  small  diameter,  of  great  height,  and 
of  very  thin  material  of  high  conductivity,  such  as  thin  enameled  iron. 
While  this  certainly  enables  the  operator  to  completely  control  the  temper- 
ature, it  has  proved  far  too  expensive  for  general  use.  But  unquestionably 
the  growing  custom  of  using  very  large  tanks  is  essentially  bad  practice. 

Activity  of  the  Yeast.  The  third  factor  in  the  problem  is  the  activity  of 
the  yeast-cell.  There  are  many  circumstances  that  modify  this  activity. 
First  it  must  be  remembered  that  the  yeasts  are  plants,  and  that,  in  a  gen- 
eral way,  their  growth  (activity)  is  modified  by  the  same  conditions  that 
affect  the  higher  plants  growing  in  the  fields.  Extremes  either  of  heat  or 
cold  are  unfavorable  to  their  maximum  development.  Thus  in  cold 
climates  the  wine-maker  keeps  a  fire  constantly  burning  in  the  fermenting- 
room,  while  in  hot  countries  all  his  energies  are  bent  on  reducing  the 
temperature  to  that  most  favorable  for  proper  fermentation. 

It  is  also  noted  that  the  higher  plants  have  different  "optimum"  tem- 
peratures ;  for  there  are  tropical  plants,  plants  of  temperate  regions,  and 
plants  that  grow  in  the  arctic  regions.  It  is  the  same,  within  certain 
limits,  with  the  yeast  plants.  This  variation  is,  as  yet,  but  little  known, 
for  it  is  within  but  a  few  years  that  serious  attention  has  been  given  to 
this  branch  of  science  so  magnificently  set  forth  by  Pasteur.  Suffice  it  to 
say  that  something  has  been  done,  and  that  the  beer  brewers  have  put 
these  principles  in  practice  with  eminent  success.  Now  the  yeast  plant  of 
the  brewers  splits  up  sugar  into  alcohol  and  carbonic  acid  gas,  just  as  the 
wine  yeasts  do,  and  is  influenced  by  exactly  the  same  conditions. 

In  the  case  of  the  seeds  of  the  higher  plants  of  all  kinds,  activity  does 
not  begin  until  the  proper  temperature  has  been  reached.  Should  the 
temperature  in  spring  rise  slowly,  the  growth  of  all  plant  life  is  corre- 
spondingly slow  ;  but  so  surely  as  a  sudden  great  rise  in  temperature  takes 
place,  plant  life  will  be  intensified  by  it  until,  when  excessive  temperatures 
are  attained,  it  is  either  paralyzed  temporarily   or  the  plant  may  die. 

Similarly,  if  the  grapes  arrive  at  the  fermenting  tank  much  heated,  then 
we  may  look  for  a  sudden  violent  development  of  yeast-plants  or  fermen- 
tation. This  is  unfavorable  for  several  reasons  :  first,  because  the  heat  is 
generated  so  rapidly  that  a  due  amount  can  not  be  carried  off  in  time  by 
conduction,  and  high  temperature  is  reached  very  quickly,  whereby  the 
yeast  may  be  paralyzed  or  killed.  But  more  than  this ;  within  certain 
limits  each  degree  of  sugar  in  the  must  means  a  corresponding  amount  of 
heat  generated  in  the  tank.  Now  if  fermentation  starts  in  at  a  low  tem- 
perature, say  56  degrees  F.,  the  generation  of  heat  will  be  slow  at  first, 
and  the  rate  of  fermentation  will  be  correspondingly  slow,  and  appare?itly 
less  heat  will  be  generated  than  if  started  at  a  higher  temperature  ;  because 
much  is  lost  by  conduction,  although  the  amount  is  actually  the  same. 
The  starting  point  was  so  low  that  the  heat  that  was  not  carried  off  by 
conduction  is  not  sufficient,  when  added  to  the  initial  temperature,  to  carry 
it  to  the  killing  point.  Let  the  initial  point  be  75  degrees  F., 
as  is  frequently  the  case,  then  the  extra  heat  added  by  the  greater 
rapidity  of  fermentation  will  carry  the  temperature,  without  doubt,  to  the 
death  limit.  Hence  the  many  efforts  made  to  get  the  grapes  into  the  tank 
in  a  cool  state.  Wherever  this  can  be  done,  the  fermentation  usually  goes 
through  well ;  but  practically  this  is  possible  only  on  a  small  scale.   Hence 


in  a  warm  climate  like  that  of  California  the  initial  temperature  of  the 
must  is  always  over  60  degrees  F.,  and  in  some  cases  over  76  degrees  F. 
The  danger  arising  from  over-heating  is,  therefore,  naturally  to  be  expected. 
Actually,  at  all  the  wineries  of  this  State,  over-heating  does  occur  almost 
continually,  and  great  financial  losses  result  therefrom. 

Nourishment.  But  aside  from  the  general  climatic  conditions,  all  plants 
are  profoundly  modified  in  their  growth  by  the  nourishment  they  receive 
from  the  soil  in  which  they  grow.  Aside  from  the  sugar  required  to 
nourish  the  yeast  plant,  one  of  the  most  important  factors  in  the  problem 
of  its  growth  is  the  acid.  There  are  other  factors,  but  these  are  not  essen- 
tial in  this  connection.  Now  just  as  there  are  plants  that  will  grow  in 
alkali  soil,  and  others  that  will  not :  so  there  are  yeast  plants  that  will 
thrive  in  a  non-acid  medium,  and  others  that  will  not. 

Diseases  of  Wine.  This  brings  us  to  the  plants  that  cause  the  diseases 
of  wine  ;  for  it  should  be  understood  once  for  all,  that  a  "  spoilt "  wine  is 
spoiled  not  spontaneously,  but  by  the  growing  in  it  of  some  minute  plant 
which  uses  the  substances  of  the  wine  to  nourish  itself,  and  to  produce 
both  its  natural  products,  most  of  which  are  foreign  to  normal  wine,  and 
unpalatable  besides.  Thus  the  bacteria  of  putrifaction  destroy  otherwise 
edible  meat  and  render  it  unfit  for  human  consumption.  In  the  same 
manner  all  diseased  or  ' '  spoilt '  wines  have  been  rendered  so  by  some 
plant  of  a  lower  order  than  the  yeast-plant  that  gave  it  its  quality. 

Importance  of  Proper  Temperature.  Returning  to  the  question  of 
temperature,  it  has  been  established  beyond  the  possibility  of  rational  dis- 
pute that,  in  the  majority  of  cases,  those  temperatures  most  favorable  to 
the  wine-yeast  plant  are  unfavorable  for  the  development  and  growth  of 
disease-plants  or  bacteria,  and  vice  versa. 

In  a  general  way  we  may  say  that  the  wine-yeast  is  a  plant  of  the 
temperate  zone,  while  the  disease  bacilli  are  plants  of  the  tropics  ;  the 
one  requiring  moderate  heat  for  its  normal  growth  and  the  other  re- 
quiring a  much  higher  temperature  in  order  to  grow  and  act  at  all. 
This  explains  the  practice  of  keeping  wine  in  cool  cellars.  This  is  a  very 
important  point.  High  temperatures  are  very  unfavorable  for  normal 
wine-yeast,  and  very  favorable  to  the  bacteria  which  cause  wines  to  spoil. 
After  the  limit  of  temperature  favorable  to  the  yeast-plant  has  been  passed, 
the  quality  of  the  wine  deteriorates  with  great  rapidity ;  not  necessarily 
because  the  wine-yeast  is  actually  killed,  nor  that  its  action  has  ceased 
altogether  ;  but  that  its  activity  has  been  checked,  and  that  the  harmful 
bacteria  have  begun  their  work  ;  producing,  not  alcohol,  carbonic  acid 
gas,  glycerine,  etc.,  but  their  own  characteristic  products  such  as  mannite, 
acetic,  lactic,  and  butyric  acids,  etc.,  etc. 

Paralysis  and  Death  of  Yeast-plants.  The  degree  of  paralysis  of  the 
yeast-plant  depends  upon  the  temperature  and  composition  of  the  must. 
The  absolute  point  of  temperature  at  which  paralysis  or  death  will  over- 
take the  yeast-plant  cannot  be  fixed  absolutely,  as  it  depends  upon  the 
variety  of  ferment  or  yeast-plant,  as  well  as  upon  the  conditions  in  which 
it  works  best.  For  normal  musts  with  a  normal  yeast,  the  death  point  is 
generally  from  98  to  100  degrees  (F).  Some  varieties  of  yeast  (and  these 
are  few)  will  stand  more  heat,  most  of  them  suffering  greatly  before  this 
point  is  reached ;    the  must  also  should  be  of  a  composition  naturally 


favorable  to  them.  Before  this  point  is  reached  the  bacteria  begin  to 
develop,  while  the  wine-yeast  stops  growth  and  the  wine,  if  not  spoiled, 
is  rendered  of  less  value  than  it  would  have  been,  had  the  temperature 
remained  lower. 

Effect  on  Bouquet  and  Aroma.  It  should  be  noted  in  this  connection 
that,  with  certain  reservations,  the  general  rule  is  that  the  lower  the 
temperature  of  fermentation  the  better  the  aroma  and  bouquet  of  the  wine. 
In  other  words,  the  proper  regulation  of  the  temperature  of  the  must 
during  the  first  or  tumultuous  fermentation  means  the  production  of  a 
wine  richer  in  alcohol,  of  better  keeping  qualities,  and  better  quality 
throughout. 

Use  of  Antiseptics'  and  Antiferments.  With  this  review  of  the  general 
principles  governing  fermentation,  we  come  to  the  practical  lessons  de- 
ducible  therefrom.  We  have  had  occasion  to  note  the  heavy  annual  loss 
to  wine-makers  from  "stuck  tanks,"  resulting  either  in  the  total  destruc- 
tion of  the  wine,  or  the  partial  loss  of  its  market  value.  We  have 
also  had  occasion  to  listen  to  the  criticisms  of  the  purchasers  of 
California  wine,  both  abroad  and  in  this  country ;  and  in  by  far  the 
greater  number  of  cases  the  fault  found  was  not  so  much  with  the  quality, 
(for  well-made  California  wine  compares  favorably,  grade  for  grade,  with 
any  in  the  world)  but  in  the  unsoundness,  i.  e.  the  tendency  to  spoil  on 
the  hands  of  the  purchaser  before  reaching  the  consumer.  This  has  led 
to  the  use  of  antiseptics,  "anti-ferments,"  that  is  poisons  which  kill  out- 
right or  paralyze,  not  only  the  wine-yeast  but  all  bacteria  that  might 
intervene,  and  in  some  cases  the  consumer  as  well.  The  making  of  wine 
at  high  temperatures  is  simply  inviting  the  use  of  antiseptics  ;  for,  as  a 
matter  of  fact,  unsound  wine  can  only  be  marketed  by  the  use  of  some  power- 
ful agent,  to  keep  the  bacteria  in  check.  Few  wine-makers  realize  the  great 
harm  done  to  the  reputation  of  Californian  wines  by  a  few  unscrupulous 
or  ignorant  dealers  who  systematically  buy  up  unsound  wines,  "doctor  " 
them,  and  ship  them  abroad.  The  sooner  the  use  of  antiseptics  of  any 
kind  (except  pure  wine  alcohol)  is  stopped,  the  better  it  will  be  for  all 
concerned  in  viticulture.  It  is  to  be  regretted  that  there  is  no  law  enforced 
that  punishes  those  who  use  dangerous  drugs  in  wine. 

Stuck  Tanks.  A  ' '  stuck  tank ' '  is  a  very  common  occurrence  at  most 
all  wineries  in  California,  as  well  as  in  all  countries  having  similar  climates. 
It  means  that  the  yeast  germs  that  convert  the  juice  of  the  grape  into 
wine  have  suddenly  ceased  their  normal  action,  and  fermentation  proper 
has  ceased,  while  bacterian  activity  has  started  up  ;  resulting  either  in  the 
total  or  partial  loss  of  the  wine.  One  wine-maker  of  this  State  told  us 
that  his  loss  from  stuck  tanks  amounted  in  a  single  season  to  $10,000; 
and  there  are  but  few  who  do  not  suffer  to  a  certain  extent  from  this  trouble. 

As  has  been  shown,  the  commonest  cause  of  stuck  tanks  is  too  high 
temperature.  The  trouble  is  not  by  any  means  confined  to  California  ; 
but  is  the  curse  of  all  wine-making  countries  in  the  warmer  parts  of  the 
world,  viz.  all  Southern  Europe,  North  and  South  Africa,  Australia,  etc. 
The  wine-maker  of  these  countries  has  been  found  to  be  less  self-compla- 
cent than  his  California  brother,  and  has  made  serious  efforts  to  control 
the  temperature  of  fermentation. 

Methods  of  reducing   Temperature.    By  some  wine-makers  the  amount 


of  sugar  was  reduced  by  the  addition  of  water.  This,  in  many  cases  proved 
of  great  service,  but  in  others  it  was  not  so  ;  for  the  water  also  reduces  the 
acid  and  the  body  of  the  wine,  and  unless  there  be  sufficient  acid,  normal 
fermentation  does  not  take  place,  save  under  exceptional  circumstances. 
Others  tried  to  reduce  the  temperature  of  the  wine  by  the  addition  of  ice 
to  the  fermenting  tank.  This  had  not  only  the  same  effect  as  the  addition 
of  water  but  proved  utterly  impracticable  in  the  case  of  red  wine  and  is 
not  economical.  Some  tried  the  use  of  metal  spiral  coils  plunged  in  the 
fermenting  tank  through  which  cold  water  was  passed.  This  proved 
successful  in  the  case  of  wine  fermenting  without  skins  or  stems  (white 
wine)  ;  but  was  impracticable  in  all  cases  where  the  skins  and  stems  were 
left  in  the  tank,  owing  to  the  impossibility  of  sufficiently  mixing  the  hot 
and  cold  parts  of  the  fermenting  mass.  Others  tried  metal  tanks,  but  this 
was  found  to  be  too  expensive. 

Again,  some  tried  pumping  the  wine  from  the  bottom  of  the  tank  over 
into  the  top  and  allowing  it  to  spread  out  in  a  spray.  This  accomplished 
two  results :  it  cooled  the  wine  slightly  (but  very  slightly)  and  especially 
did  it  revive  the  partially  paralyzed  yeast  cells  by  giving  them  a  fresh 
supply  of  free  oxygen.  The  fatal  defect  of  this  practice  was  found  to  be 
that  too  great  oxidation  and  evaporation  of  the  alcohol,  which  took  place 
at  high  temperatures,  the  wine  becoming  too  highly  charged  with  acetic 
acid  (vinegar-sour).  Nevertheless,  this  pumping  over  of  the  wine  of  stuck 
tanks,  or  tanks  that  threaten  to  stick,  is  now  widely  practiced  all  the 
world  over,  and  in  the  case  of  a  sudden  stopping  of  fermentation  it  is 
necessarily  done  to  supplement  the  addition  of  fresh  must  in  active  fermen- 
tation used  to  finish  the  conversion  of  the  sugar  into  alcohol  and  carbonic 
acid  gas. 

Experiments  at  the  University,  Convinced  of  the  necessity  of  control- 
ling the  temperature  of  the  fermentation  of  wines  in  this  State,  (just  as  the 
brewers  do  that  of  their  fermenting  wort  to  a  fraction  of  a  degree,  always 
getting  a  product  the  value  of  which  is  known  beforehand),  the  Viti- 
cultural  Staff  of  the  College  of  Agriculture  set  about  to  devise  some  pract- 
ical method  for  attaining  this  end.  It  was  only  after  having  completed 
the  experiments  with  the  apparatus  herewith  described,  that  we  received 
detailed  data  of  the  European  experiments  with  the  refrigeration  of  wine. 
We  give  below  a  complete  description,  first,  of  the  French  apparatus; 
second,  of  the  one  first  devised  at  the  Experiment  Station  ;  and,  third,  of 
the  one  modified  as  found  advisable  after  thorough  trial. 

Apparatus  used  in  other  Countries.  Figure  i  represents  one  of  the 
forms  of  the  apparatus  now  used  throughout  Northern  Africa  and  South- 
ern France.  As  will  be  seen,  it  consists  essentially  of  two  columns,  each 
made  up  of  nineteen  thin,  well-tinned,  horizontal  copper  tubes.  These 
tubes  are  i$%  feet  long  by  i^  inches  in  diameter.  The  total  length  of 
the  tubes  through  which  the  wine  passes  is  thus  nearly  500  feet.  These 
tubes  are  fitted  into  solid  bronze  castings  closed  by  means  of  a  bronze  plate 
over  a  rubber  washer,  with  thumb  screws.  The  two  columns  are  con- 
nected by  a  tube  (3  fig.  1)  running  diagonally  from  the  top  of  one  column 
to  the  bottom  of  the  other,  so  that  the  hot  wine  entering  at  the  lower  end 
(7  fig.  1)  of  the  first  column,  and  after  passing  upwards  and  completing  the 
circuit  in  this  column,    passes  to  the  bottom  of  the  second  column,  from 


Fier.  i. 


which  again  it  escapes  at  the  top.  Above  the  two  columns  of  tubes  is  a  large 
metal  water-box,  having  two  rows  of  holes  in  the  bottom  corresponding 
to  the  two  columns,  from  which  cold  water  is  allowed  to  drip  as  the  warm 
wine  is  pumped  through  the  tubes.  Under  the  apparatus  is  a  metal  box 
which  catches  the  drip  of  warmed  water.  Each  column  of  tubes  has  a 
stop-cock  (13)  which  allows  rapid  emptying  of  the  wine  when  pumping 
is  stopped.  The  apparatus  is,  as  before  said,  now  actually  in  use  in  other 
countries  and  we  are  indebted  to  the  excellent  report  of  Messrs.  Mlintz  and 
Rousseaux  in  La  Revue  de  Viticulture  for  the  results  of  their  exhaustive 
experiments  conducted  in  France  during  the  past  season,  1896,  as  well  as 
during  the  season  of  189^. 

The  first  defects  that  strike  one  in  this  apparatus  is  the  unwieldiness 
and  expense,  as  well  as  the  large  amount  of  labor  required  to  force  a  one- 
and-a-half  inch  stream  of  wine  through  such  a  length  <  f  tubing  at  a  work- 
ing rate ;  then  the  amount  of  water  used  in  cooling  the  wine  must  be  very 
large,  unless  the  temperature  of  this  water  be  considerably  below  that  of 


the  wine.     As  in  the  case  of  the  use  of  ice,  it  will  do  well  when  all  con- 
ditions are  most  favorable. 

In  a  recent  article,  giving  a  resume  of  the  two  seasons'  experiments, 
Messrs.  Miintz  and  Rousseaux  tell  us  that  to  work  the  apparatus,  a  gang 
of  four  men,  working  in  relays,  is  required  to  pump  forty  hectoliters  or 
1060  gallons  per  hour.  With  a  motor  engine,  double  this  amount  could 
be  pumped  through,  but  the  quantity  of  water  needed  in  this  case  for  the 
proper  cooling  of  the  wine  is  enormous,  amounting  to  from  one  to  one-and- 
one-half  times  the  amount  of  wine  passed  through  ;  or  far  more  cold  water 
than  is  generally  to  be  had  at  the  average  California  winery. 

The  reduction  of  temperature  was  in  some  cases  very  great,  but  de- 
pended altogether  upon  the  rate  of  pumping,  the  amount  of  water  dripping 
over  the  tubes,  and  the  initial  temperature  of  this  water.  There  was  an 
average  reduction,  however,  of  from  10  to  12  degrees  F.,  but  in  some  cases 
a  maximum  of  as  much  as  20  degrees  when  slow  pumping  was  practiced. 
The  cost  of  cooling  the  wine  was,  on  an  average,  one-thirteenth  of  one 
cent  per  gallon. 

From  the  careful  tests  made  by  these  eminent  scientists,  the  remarkable 
benefits  of  cooling  the  fermenting  mass  was  strikingly  shown.  In  all 
cases  a  certain  lot  of  the  same  must  was  fermented  in  the  usual  way  as  a 
check  to  the  experiment,  and  in  every  case  the  cooled  wine  was  sounder 
and  of  far  better  quality.  Microscopic  examination  showed  that  the  un- 
cooled  wine  was  teeming  with  harmful  bacteria,  while  the  amount  of 
unfermented  sugar  remaining  was  very  considerably  more  than  in  the  case 
where  the  wine  had  been  cooled.  The  University  experiments  showed 
this  as  strikingly  as  did  those  of  Miintz  and  Rousseaux. 

We  give  below  a  table  taken  from  La  Revue  de  Viticulture  in  which 
some  of  these  results  are  set  forth.  Unfortunately  the  recent  disastrous 
fire  at  the  Agricultural  Building  at  the  University  destroyed  all  the  notes 
taken  at  each  tank  cooled,  so  that  we  can  but  give  the  general  results. 
These  results  were,  however,  looked  over  but  a  few  days  before  the  fire  and 
being  compared  with  those  made  in  France  by  Miintz  with  his  apparatus 
were  found  to  be  essentially  in  accord,  as  appears  from  the  data  given  below. 
We  give  below  the  exact  figures  obtained  by  these  observers.  This  shows 
the  matter  to  be  not  of  something  "theoretical"  and  untried,  but  something 
that  has  been  tried  by  several,  and  proved  to  be  a  practical  success. 

The  experiments  were  made  in  the  Roussillon  district  of  France,  near 
the  Eastern  Pyrenees,  during  the  season  of  1896,  with  Carignane  grapes. 


Maximum  tem- 
perature of  the  must 

Alcohol  per  cent. 

Unfermented 
Sugar. 

during  fermentation 

1 1. OO 

Cooled  Wine 

96     (F.) 
96.8 

99-5 
102.2 

( i                <  < 

n-45 

•59 

U                      (I 

11.50 

.65 

Uncooled  Wine 

10.20 

2.6o 

1 1             <( 

104.0 

10.10 

3-3° 

It  will  be  recollected  that  experiments  made  by  Prof.  Hilgard  at  the 
University,  in  1887,  gave  almost  precisely  similar  results  as  to  alcohol  per- 
centage when  hot  and  cool  fermentations  were  compared.      (See  Report 


of  the  College  of  Agriculture    on  Methods  of  Fermentation  of  1886-87, 
p.  28.) 

The  effects  of  high  temperature  on  the  composition  of  the  wine  may  be 
further  illustrated  by  some  other  analytical  results  from  the  French  experi- 
menters, Miintz  and  Rousseaux,  who  found  in  1895  that  a  wine  which  had 
attained  a  maximum  temperature  of  98.5  degrees  F.,  during  fermentation 
showed  on  analysis  .066  percent  of  ammonia,  while  another  wine  made 
from  the  same  lot  of  grapes,  which  attained  a  maximum  of  104  degrees, 
showed  .60  percent.  Similar  results  were  obtained  in  1896,  when  maxima 
temperatures  of  94  degrees  and  104  degrees  gave  .03  percent  and  .22  per- 
cent of  ammonia  respectively.  It  is  clear,  therefore,  that  serious  chemical 
differences  and  defects  are  produced  in  the  wine  by  high  temperature 
fermentations  apart  from  the  swarms  of  disease  bacteria  which  are  always 
present  in  such  wine.  Of  the  wines  made  by  Miintz  and  Rousseaux  in 
their  1896  experiments,  those  that  were  not  cooled  threaten  to  spoil  al- 
ready ;  while  those  that  were  cooled  are  in  perfect  condition. 


EXPERIMENTS    MADE    BY   THE   UNIVERSITY   AT   NATOMA,    SACRAMENTO 
COUNTY,    AND   AT    EVERGREEN,    SANTA    CLARA    COUNTY. 

Apparatus  used.  The  results  of  Miintz  and  Rousseaux  were  amply  con- 
firmed by  the  investigations  undertaken  by  the  Viticultural  Staff  during 
the  season  of  1896  at  the  Natoma  Vineyard  in  Sacramento  County,  and  at 
Mr.  Wehner's  at  Evergreen,  near  San  Jose.  The  apparatus  used  by  us 
differed  greatly  from  that  used  by  Miintz  and  Rousseaux,  and  the  many 
others  abroad  who  practiced  refrigeration  during  fermentation  at  the  same 
time. 

Not  being  able  to  avail  ourselves  of  the  detail  of  the  numerous  experi- 
ments undertaken  along  the  same  lines  abroad  during  the  past  few  years, 
we  had  to  construct  our  apparatus  independently  upon  what  we  considered 
the  most  promising  lines  ;  fortunately,  as  it  turned  out,  committing  few 
mistakes  and  obtaining  results  that  show  our  system  to  be  far  superior  to 
any  thus  far  proposed  for  California  conditions.  However,  experience 
has  shown  us  the  desirability  of  certain  changes  and  modifications  as 
hereinafter  shown,  especially  as  mechanical  power  for  pumping  and  crushing 
is  available  at  nearly  all  wineries  of  this  State. 

The  apparatus  shown  in  figure  2  is  the  one  designed  and  used  by  us 
in  the  experiments.  It  will  be  observed  that  insofar  as  the  pumping  of 
the  heated  wine  through  tinned  copper  tubes  goes,  the  principles  are 
identical  with  those  of  the  French  apparatus.  The  method  of  pumping 
is  the  same  as  is  in  practice  at  wineries  for  drawing  off  the  newly  fer- 
mented wine  from  the  fermenting  tank.  The  wine  is  drawn  off  from  the 
bottom  of  the  tank  and  strained  through  a  sieve  into  a  tub,  from  which  it 
is  pumped  through  the  apparatus  into  the  top  of  the  tank  again.  In  other 
respects  there  are  important  differences  ;  thus,  instead  of  two  columns  con- 
sisting of  498  lineal  feet  of  tubing,  our  apparatus  consisted  of  a  single 
column  of  only  42  feet  of  tubing.  The  tinned  copper  tubing  instead  of 
being  perfectly  round  is  very  much  flattened,  thereby  giving  greater  cooling 
surface  to  the  same  volume  of  wine,  a  material  improvement  on  the  French 


. *»wj.»-frrrw»*rTT    -Iff] f*  '      "  Tl 

1 -^Jlil 


II 


system  of  round  tubes.  It  consists  of  14  pieces  3  feet  long  and  4  inches 
broad,  by  1%  inches  deep.  These  tubes  are  fitted  into  bronze  castings 
which  are  closed  by  plates  fitting  over  rubber  washers,  and  fastened  by 
thumb-screws,  thus  allowing  the  tubes  to  be  readily  cleaned  in  cases  of 
obstructions  that  might  occur  in  the  pumping  through  of  the  muddy, 
partly  fermented  must. 

METHODS    OF    COOLING. 

Water-box.  In  our  first  experiments  the  whole  apparatus,  that  is 
to  say  the  column  of  tubes,  was  fitted  into  a  box,  tin-lined  and 
filled  with  water.  A  constant  supply  of  fresh  water  entered  the  box 
at  the  bottom,  escaping  from  the  top,  while  the  wine  entered  the  top  of  the 
apparatus  and  escaped  at  the  bottom,  in  order  that  the  coldest  zvine  should 
come  in  contact  with  the  coldest  water,  and  vice  versa.  It  is  well  known 
that  this  arrangement  will  give  the  greatest  amount  of  cooling  effect. 

It  was  found  that  by  the  use  of  a  very  large  quantity  of  water  the  wine 
could  be  sufficiently,  cooled,  but  the  excessive  amount  of  water  thus  re- 
quired caused  us  to  abandon  this  system.  In  special  cases,  where  an 
unlimited  water  supply  is  to  be  had  without  too  great  expense,  this  system 
should  be  adopted,  for  though  the  cost  of  water-box  and  installation  will 
about  offset  the  cost  of  the  blower  and  canvas  sleeve,  hereinafter  described, 
it  has  the  advantage  of  doing  away  with  the  necessity  of  the  command 
of  power.  In  case  this  system  is  adopted,  it  is  well  to  use  a  greater  length 
of  tubing  than  would  be  required  where  the  spray  and  the  air  current  are 
used.  Roughly  speaking,  the  amount  of  water  used  in  this  case  should 
be  from  \y2  to  2^  times  the  volume  of  wine  pumped  through  the  apparatus. 

Drip,  Spray  and  Blast.  Instead  of  depending  upon  the  simple  dripping 
of  the  water  over  the  tubes  to  effect  the  reduction  of  temperature  of  the 
warm  wine,  a  great  saving  of  tubing,  as  well  as  labor  in  pumping,  was 
found  to  be  effected  by  the  use  of  a  fine  spray  of  water  carried  by  a  strong 
blast  of  air,  thus  combining  the  effects  of  cold  water  and  evaporation.  The 
quick  evaporation  brought  about  by  the  dry  air  prevailing  at  our  vintage 
season,  when  mingled  with  a  fine  spray,  produces  a  cooling  effect  far  in 
excess  of  what  could  be  obtained  from  the  ordinary  water  at  the  wineries 
alone.  This  is  important,  for  at  many  of  the  wineries  the  water  available 
is  very  warm  and  the  difference  between  the  temperature  of  the  water  and 
the  wine  to  be  cooled  is  so  slight  that  it  would  be  impossible  to  effect  a 
proper  amount  of  cooling,  unless  enormous  volumes  of  water  were  used. 

The  proper  proportions  between  the  air  blast  and  the  amount  of  water 
sprayed  is  of  the  utmost  importance.  It  is  readily  understood  that  a  weak 
blast  with  a  large  amount  of  coarsely-sprayed  water  would  leave  the  tem- 
perature of  the  water  almost  unchanged  when  it  reaches  the  cooler,  and 
would,  therefore,  amount  to  little  more  than  the  dripping  practiced  in  the 
French  apparatus ;  while  if  the  blast  be  in  excess  and  the  water  deficient, 
the  amount  of  water  carried  may  not  be  sufficient  to  utilize  the  evaporative 
power  of  the  blast,  nor  to  thoroughly  wet  the  tubes.  Again,  to  insure  the 
maximum  cooling  from  evaporation,  the  spray  should  be  so  fine  that 
within  the  short  distance  from  the  nozzle  to  the  tubes  the  air  may  become 
fully  saturated,  and  both  cooled  to  the  fullest  extent.  Of  course,  the 
heavier  the  blast,  the  more  water  spray  can  be  carried  and  cooled  by  it. 


12 


To  produce  the  requisite  fineness  of  spray,  an  adequate  water  pressure  is 
necessary. 

Another  factor  of  the  utmost  importance  is  the  dryness,  or  what  is 
technically  called  the  "relative  humidity"  of  the  air  used.  During  the 
vintage  season  this  is  frequently  as  low  as  33%  outside  of  the  ivi?iery; 
and  the  intense  evaporating  effect  producible  under  such  conditions  should 
be  utilized  by  connecting  the  intake  with  the  outer  air.  This,  of  course, 
can  be  done  either  by  a  canvas  tube  stretched  by  hoops,  or  by  a  board  flume. 

When,  as  may  happen  near  the  coast,  the  moist  condition  of  the  air  is 
unfavorable  to  strong  evaporation,  the  water  temperature,  on  the  contrary, 
is  frequently  itself  so  low  that  an  energetic  spray  without  a  blast  may  suf- 
fice to  do  the  necessary  amount  of  cooling. 

It  will  be  noted,  therefore,  that  the  best  conditions  for  cooling  will  vary, 
not  only  in  different  localities,  but  on  different  days,  and  according  to  the  pre- 
vailing wind  ;  so  that  it  is  impossible  to  prescribe  the  exact  strength  of 
blast  or  quantit}'  of  spray  that  should  be  used.  But  a  few  experiments 
will  determine  the  best  practice  in  any  given  locality. 

In  our  experiments  the  blast  of  air  was  generated  by  means  of  an  18-inch 
"double"  (8-wing)  blower,  or  "exhaust-fan"  reversed.  The  water 
escaped  from  a  battery  of  three  Vermorel  nozzles  placed  immediately  in 
front  of  the  blower. 

A  conical  canvas  sleeve  attached  to  the  outlet  of  the  blower  and  five 
and  one-half  feet  away  to  the  circumference  of  the  cooler-frame  prevents 
the  loss  of  blast  and  spray. 

The  "double"  18-inch  blower  requires  under  ordinary  circumstances 
less  than  one-half  horse-power  to  run  it  at  a  rate  of  1000  revolutions  per 
minute,  and  thus,  with  a  free  supply,  will  pass  3000  cubic  feet  per  minute 
through  it.  The  24-inch  "double"  blower  requires  about  the  same 
horse-power  to  run  it,  but  requires  only  900  revolutions  per  minute  to 
send  through  5000  cubic  feet  in  the  same  time.  It  should  be  remembered 
that  the  best  efficiency  of  every  blower  is  limited  to  a  definite  velocity  of 
revolution.  The  figures  above  given  refer  to  the  most  favorable  velocities 
for  the  sizes  mentioned.  The  one  costs  $40.00  (less  discount)  while  the 
latter  costs  $50.00.  In  order  that  the  apparatus  may  be  available  at  small- 
scale  wineries,  where  no  steam  is  used,  it  may  be  well  to  state  that  a  small 
gas  engine,  run  with  common  "distillate"  and  giving  two  and  one-half 
horse-power,  can  be  had  for  $187  (less  discount).  The  cost  of  running  such 
a  motor  is  one  cent  per  horse-power  per  hour;  a  trifling  expense,  especially 
as  the  motor,  once  started,  will  run  itself,  so- that  one  man  can  attend  to 
the  pumping  of  the  wine  and  the  running  of  the  engine  at  the  same  time. 
Indeed,  with  a  little  fitting,  such  an  engine  could  be  made  to  do  all  the 
pumping  in  the  cellar,  and  there  are  no  laborers  who  will  do  one  horse- 
power of  work  for  a  cent  an  hour. 

While  the  French  apparatus  was  movable,  ours  was  of  necessity  fixed, 
but  with  one  man  at  the  pump  at  Mr.  Wehner's  place  it  was  found  that 
he  could  pump  from  the  most  distant  tank  at  the  rate  of  1000  gallons 
per  hour,  in  some  cases  as  much  as  1400  gallons.  At  this  rate  a  reduction 
of  temperature  of  from  10  to  13  degrees  was  obtained  in  the  wine.  The 
temperature  was  taken  at  the  point  where  the  wine  left  the  tank  and  again 
where  it  re-entered  the  tank  after  having  passed  through  the  cooler. 


13 

Precautions.  We  found  that  the  much-feared  deposit  of  cream  of  tartar 
on  the  inside  of  the  tubes  was  very  slight  indeed.  It  would  seem  that 
while  warm  wine  on  cooling  will  deposit  cream  of  tartar  on  the  lining  of 
the  vessel,  wine  constantly  in  motion  (as  when  being  pumped)  will  not 
deposit  much.  Even  after  long  use  it  was  found  that  the  thin  coating  of 
cream  of  tartar  on  the  inside  of  the  tubes  could  be  removed  by  pumping 
the  apparatus  full  of  water  and  leaving  it  over  night  after  a  few  barrels 
had  been  pumped  through.  The  apparatus  should  be  flushed  out  at  least 
once  in  twenty-four  hours,  for  the  deposit  of  cream  of  tartar,  be  it  ever  so 
slight,  interferes  greatly  with  the  conduction  of  heat,  and  anything  that 
has  this  effect  must  be  carefully  avoided.  Even  the  surface  of  the  tubes 
should  be  polished  once  a  day  with  ashes  or  lye,  for  there  forms  on 
the  surface,  after  a  day's  use,  a  "greasy"  film,  due  to  the  lubricant 
necessarily  used  in  the  blower,  which  not  only  interferes  with  the  con- 
duction of  heat,  but  causes  the  water  to  run  in  streaks  over  the  surface 
instead  of  spreading  over  it,  much  cooling  surface  being  thus  lost. 

The  seeds  and  skins  should  be  kept  out  as  well  as  possible  from  the 
pump  and  consequently  from  the  apparatus.  By  exercising  due  precaution 
in  this  regard,  we  did  not  have  to  clean  the  apparatus  from  this  cause  once 
during  the  entire  trial. 

Control  of  Temperature.  We  found,  as  did  Miintz  and  Rousseaux,  that 
when  the  wine  passed  ioo  degrees,  cooling  was  useless,  for  the  ferments 
or  yeasts  were  too  badly  injured  to  be  revived.  Thus  a  tank  at  Natoma 
(where  the  conditions  were  unfavorable  on  account  of  hot  weather)  was 
fermented  with  some  Algerian  yeast,  and  was  allowed  to  go  as  high  as 
104  degrees.  The  tank  "stuck"  before  fermentation  was  finished  and  it 
could  not  be  revived  b}r  cooling. 

Miintz  and  Rousseaux  state,  that  if  a  tank  is  cooled  before  the  tem- 
perature reaches  the  danger  limit,  there  need  be  no  fear  that  a  subsequent 
rise  to  this  limit  will  take  place.  We  found  at  Mr.  Wehner's  that  under 
the  conditions  existing,  when  the  temperature  in  the  tank  reached  88 
degrees,  if  we  pumped  about  one-half  or  two-thirds  of  the  contents  of  the 
tank  through  the  cooler,  nothing  disastrous  ever  happened,  although  the 
fermentation  kept  right  on  and  the  rise  in  temperature  continued,  yet  it 
seemed  that  a  sufficient  amount  of  heat  (calories)  had  been  removed  from 
the  fermenting  mass  to  enable  it  to  complete  the  fermentation  without 
reaching  the  danger  point.  This  favorable  result,  however,  must  largely 
depend  upon  special  conditions,  and  should  not  be  relied  upon  so  as  to 
relax  vigilance. 

Considering  the  fact  that  low  temperature  fermentation  gives  a  wine  of 
a  different  composition  from  that  fermented  at  high  temperature,  and 
leaving  for  the  moment  the  killing  of  the  yeast  out  of  the  question,  it  is 
evident  that  it  would  pay  to  keep  the  temperature  constantly  below  the 
danger  limit  on  account  of  the  superior  quality  of  the  resulting  wine. 

It  might  not  pay  in  ordinary  cases  to  go  to  this  expense  for  quality 
alone,  yet  if  extra  fine  wine  is  to  be  made,  extra  care  must  be  bestowed 
upon  it. 


14 

Aeration  of  the  Wine.  It  was  deemed  advisable  to  aerate  the  wine 
whenever  it  was  pumped  over.  In  order  to  accomplish  this,  and  at  the 
same  time  to  prevent  the  cooled  wine  from  forming  a  channel  in  the  cap 
and  passing  at  once  to  the  bottom  and  thus  leaving  the  warmer  wine  at 
the  top,  we  caused  the  wine  to  escape  from  the  end  of  the  ho.se  in  a  fanlike 
jet,  the  direction  of  which  was  from  time  to  time  so  changed  as  to  reach 
all  parts  of  the  cap  during  the  cooling.  In  this  way  the  cap  was  very 
greatly  cooled,  which  is  important  as  it  is  the  hottest  part  of  the  ferment- 
ing mass  in  a  tank. 

In  all  cases  where  the  cooling  took  place  at  or  about  88  degrees,  the 
tank  "went  dry"  perfectly  well,  and  the  resulting  wine  was  drier  and  far 
clearer  than  in  case  of  the  wine  not  cooled  and  aerated.  This  was  especially 
noticeable  in  cases  where  pure  cultures  of  yeast  were  used,  especially  some 
of  the  foreign  varieties. 

In  some  cases  we  tried  the  use  of  an  extra  empty  tank  into  which  the 
cooled  wine  from  the  first  tank  pumped  was  put,  and  the  cooled  wine  from 
subsequent  tanks  was  pumped  into  the  first  tank.  At  the  end  of  a  certain 
time  the  wine  first  cooled  was  pumped  into  the  last  tank.  In  this  way 
one  avoids  cooling  the  same  wine  or  part  of  it  twice,  but  an  extra  pump- 
ing is  thus  necessitated.  The  avoidance  of  cooling  wine  that  has  just  been 
cooled  and  pumped  back  to  the  top  of  the  tank  is  certainly  an  important 
problem  that  must  be  solved  by  each  wine-maker  according  to  circum- 
stances. We  would  suggest  that  a  storage  tank  at  a  greater  elevation 
than  the  fermenting  tank  be  used  as  a  common  receptacle  for  all  cooled 
wine.  As  soon  as  a  sufficient  amount  of  wine  in  any  given  tank 
has  been  cooled,  it  can  be  returned  by  gravity,  and  thus  all  danger  of 
wasting  energy  by  pumping  the  same  wine  twice  through  the  cooler  can 
be  avoided.  It  is  true  that  there  will  be  an  extra  amount  of  labor  required 
to  force  the  cooled  wine  to  a  greater  level  than  that  of  the  fermenting  tank. 

Faults  of  the  Apparatus .  It  was  found  that  with  our  first  apparatus  we 
had  made  the  mistake  of  placing  the  tubes  too  far  apart  (2^  inches),  los- 
ing thereby  a  very  considerable  amount  of  air  and  spray.  This  we  had  to 
remedy  for  the  time  by  filling  up  the  space  with  two-inch  slats  ;  but  this, 
of  course,  caused  a  great  waste  of  cooling  effect.  We  therefore,  in  our 
modified  apparatus,  recommend  that  the  tubes  be  placed  an  inch  apart, 
which  is  the  practical  limit  for  the  successful  soldering  of  the  tubes  into 
the  castings,  more  especially  when  the  tubes  are  of  such  greater  width  as 
we  now  find  desirable.  The  horizontal  position,  moreover,  will  always 
prove  a  source  of  waste  on  account  of  allowing  too  ready  a  passage  for  the 
current  of  air  and  spray.  It  was  also  found  that  for  large  scale  operations 
the  cooling  capacity  of  the  apparatus  was  not  adequate. 


THE   NEW   APPARATUS. 

In  the  construction  of  the  new  apparatus  the  need  of  greater  capacity 
was  first  considered.  The  lengthening  of  the  tubes  as  in  the  French 
model  renders  it  very  cumbersome,  and  it  therefore  seemed  preferable 
to  retain  the  .  same  length  of  tubes,  but  to  give  them  an  increased 
cooling  surface  by  enlarging  their  dimensions  to  5 )A  xi)4  inches,  and  to 


15 

use  two  batteries  or  columns  placed  one  behind  the  other.  This  arrange- 
ment would  serve  in  any  case  to  utilize  better  the  cooling  current  which 
must  always  waste  through  a  single  system  of  tubes  however  placed. 
Moreover,  the  increased  cooling  surface  obtained  by  widening  the  tubes 
does  not  involve  an  increase  of  friction,  as  would  a  lengthening  of  tubes, 
to  attain  the  same  purpose. 

Another  modification  deemed  wise  is  to  have  the  extremities  of  the 
tubes  closed  by  a  single  bronze  casting  instead  of  separate  castings  for  each 
pair  of  tubes.  These  castings  are  fastened  by  thumb-screws  over  rubber 
washers,  as  in  the  case  of  the  first  machine.  The  advantages  are  that  it 
not  only  requires  fewer  thumb-screws  (and  hence  allows  greater  rapidity 
in  cleaning),  but  also  that  the  solidity  of  the  whole  apparatus  is  greatly 
enhanced,  and  the  necessity  for  an  extra  frame  is  done  away  with.  We 
found  that  with  the  great  number  of  small  castings  it  was  difficult  to  keep 
any  frame  from  "  giving  "  a  little.  (See  Fig.  3.) 

Relative  Position  of  the  Sets  of  Tubes.  In  order  to  determine  as 
nearly  as  possible  the  various  conditions  needful  to  secure  the  best 
results,  two  sets  of  tubes  of  twelve  each  were  placed  in  a  convenient  frame, 
and  so  suspended  on  chains  that  both  their  distance  and  their  relative  po- 
sitions could  be  readily  changed  at  will.  While  this  would  not  enable  us 
to  determine  exactly  all  the  best  conditions  in  the  completed  arrangement, 
it  would  at  least  enable  us  to  avoid  such  mistakes  as  rendered  the  first  ap- 
paratus to  some  extent  unsatisfactory. 

It  soon  became  apparent  that  so  long  as  the  tubes  in  the  two  sets  were 
placed  parallel  to  each  other,  whether  horizontally,  or  inclined  upwards  or 
downwards,  even  when  arranged  as  closely  as  practically  possible,  and  so 
as  to  break  joint,  there  was  a  great  waste  of  spray,  and  therefore  of  cool- 
ing power,  in  the  rear  of  the  second  column.  The  obvious  remedy  was  to 
place  them  at  an  angle  to  each  other,  so  that  the  current  should  be  con- 
siderably checked  and  its  direction  completely  changed  before  being 
allowed  to  emerge  at  the  rear  end  of  the  apparatus.  It  remained  to  be 
determined  whether  the  relative  inclinations  should  be  in  the  form  of  a  V 
or  of  an  A,  and  what  the  angle  of  the  inclination  should  be.  It  wras 
evidently  not  desirable  to  make  this  angle  steeper  than  necessary  to 
accomplish  the  purpose. 

Points  observed.  In  making  the  experiments  the  points  observed  were  : 
First,  the  absence  of  any  considerable  waste  of  spray  beyond  the  second 
column  ;  second,  the  approximate  equality  of  the  drip  of  water  from  both 
sets ;  third,  the  diminution  of  temperature  obtainable  with  varying  strength 
of  spray  and  blast.  We  could  thus  as  nearly  as  possible  estimate  the 
results  likely  to  be  obtained  by  the  apparatus  w7hen  completed.  In  all 
experiments  so  far  made  the  two  sets'  were  placed  as  near  together  as 
practically  possible.  As  to  the  first  point  it  w-as  found  that  the  least  waste 
of  spray  occurred  when  the  tubes  were  placed  one  inch  apart  in  the  in- 
verted V  (A)  position,  and  that  for  this  purpose  an  angle  of  30  degrees 
was  sufficient. 


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Second,  it  was  further  found  that  under  these  conditions  the  drip  from 
the  two  sets  of  tubes  was  most  nearly  equalized,  and  that  their  entire  sur- 
faces remained  well  wetted. 

As  regards  the  third  point,  it  was  found  that  in  the  space  between  the 
two  sets  the  temperature  was  mainly  governed  by  the  strength  of  the  blast 
and  the  amount  and  kind  of  spray  used.  In  this  respect  our  preliminary 
experiments  could  give  only  comparative  values,  since  the  saturation  of 
the  air  at  Berkeley  at  the  time  was  between  75  and  80  percent,  and  the 
air  temperature  varying  but  slightly  above  and  below  60  degrees  F. 


Fig.  4.     Blower. 


Air  Blast  and  Spray.  No  mechanical  power  being  available  at  the 
time  at  Berkeley,  we  had  to  restrict  ourselves  in  the  use  of  the  blower  to 
such  a  velocity  as  could  be  obtained  by  the  power  of  two  men,  which  was 
between  700  and  750  revolutions  per  minute,  obtaining  probably  about 
Yz  to  y±  of  the  effect  of  the  blower,  or  about  2000  or  2500  cubic  feet  per 
minute. 

It  was  quickly  noted  that  as  transmitted  through  the  pyramidal  canvas 
sleeve  directly,  the  distribution  of  the  wind  over  the  surface  of  the  tubes 
was  very  unequal,  being  very  strong  at  the  circumference  and  almost  null 
in  the  middle,  on  account  of  the  centrifugal  action  of  the  blower.  This 
inequality  was  effectually  done  away  with  by  the  interposition  between 
the  blower  and  the  pyramidal  sleeve  of  a  cylindrical  sleeve  3^2    feet  long. 

As  regards  the  spray,  a  comparison  of  the  reduction  of  temperatures 
obtained  with  the  rather  coarse  spray  heretofore    employed,    with  that 


i8 

obtained  from  a  standard  cyclone  nozzle  yielding  very  fine  spray,  showed 
that  the  latter  was  by  far  the  most  efficacious,  besides  which  it  permits 
of  a  shortening  of  the  pyramidal  portion  of  the  sleeve  on  account  of  the 
rapidity  with  which  evaporation  can  take  place.  To  attain  this  end,  how- 
ever, it  is  necessary  .that  the  pressure  should  be  sufficiently  high,  that  is 
nearly  such  as  is  obtained  with  spray  pumps — not  less.  Manifestly  the 
coarse  spray  carried  with  it  too  much  of  the  original  high  temperature  of 
the  water.  It  was  also  found,  however,  that  a  single  nozzle  of  this  kind 
does  not  yield  a  sufficiently  large  quantity  of  water,  and  that  therefore  a 
combination  or  battery  of  such  nozzles  should  be  used,  varying  i?i  number 
according  to  the  water  pressure  and  the  strength  of  blast  at  command.  In 
our  apparatus  we  have  adopted  five  as  probably  sufficient. 

It  is  easy  to  so  arrange  the  battery  of  nozzles  as  to  conform  to  the  flare 
of  the  pyramidal  sleeve,  in  order  not  to  waste  the  spray  upon  the  canvas  on 
the  one  hand,  nor  to  leave  part  of  the  space  unutilized  on  the  other. 

Beneath  the  apparatus  should  be  placed  a  shallow  box  to  catch  the 
drip,  which  should  be  drained  off  through  a  pipe  or  trough.  A  screen 
mas'  be  placed  in  the  rear  of  the  apparatus  to  catch  the  spray  that  has 
passed  through,  and  may  be  of  boards,  sacks  or  anything  that  is  con- 
venient. If  the  apparatus  be  placed  facing  a  door  or  window,  no  screen 
is  necessary.  The  current  of  air  in  itself  is  not  objectionable  in  a  hot 
winery.  The  drawback  to  the  free  circulation  of  the  current  of  air  and 
spray  is  that  the  workmen  working  immediately  in  front  of  it  after  coming 
from  some  hot  part  of  the  cellar  are  in  danger  of  contracting  colds  or  even 
pneumonia. 

Conclusions.  Accepting,  then,  the  fact  that  in  California  the  tendency 
is  to  ferment  at  high  temperatures  on  account  of  the  initial,  as  well  as  the 
air,  temperatures  being  higher  than  in  cooler  countries,  such  as  the  Medoc, 
Burgundy,  the  Rhine,  Champagne,  etc.,  and  also  the  fact  that  in  this 
State  we  use  exceptionally  large  fermenting  tanks,  and  that  our  musts 
are,  as  a  rule,  very  high  in  sugar  and  in  man}'  cases  low  in  acid,  the 
simple  question  is  :  Shall  we  not  attempt  to  overcome  these  natural  defects 
of  our  climate,  and  control  fermentation  just  as  wine-makers  of  other 
countries  do  under  similar  circumstances,  and  as  the  brewers  have  long 
done  under  all  circumstances  ? 

Competition  is  now  so  keen  that  if  we  would  succeed  we  must  place  on 
the  market  a  wine  that  is  equal,  if  not  superior  to,  that  of  other  countries. 
Under  favorable  conditions  we  produce  a  wine  that  is  equal  to  any  in  the 
world,  but  under  unfavorable  conditions  we  make  wines  that  are  distinctly 
inferior. 

It  is  the  custom  at  all  the  wineries  of  the  State,  in  case  of  the  tank 
threatening  to  "sick",  to  pump  the  wine  from  the  bottom  over  the  top,  at 
the  same  time  aerating  it  by  causing  it  to  fall  in  a  spray.  Should  the 
cooling  apparatus  be  used  in  connection  with  this  procedure,  there  would 
be  no  extra  cost  beyond  the  original  expense  of  the  apparaUis ,  which  will 
last  indefinitely  with  proper  care. 

An  apparatas  such  as  we  recommend  will  cost  very  little  compared  with 
the  enormous  saving  that  can  be  effected  in  a  single  unfavorable  season. 
To  provide  several  for  use  at  a  large  winery  should  not  cost  over  $1,000, 


19 

while  for  a  winery  of  ordinary  size  an  apparatus  capable  of  reducing  the 
temperature  of  the  wine  a  minimum  of  10  deg.  at  the  rate  of  1,000  gallons 
per  hour,  would  cost  far  less.  Messrs.  Miintz  and  Rousseaux  found  that 
the  cost  of  cooling  wine  in  France  with  their  cumbersome  apparatus  was 
1/13  of  a  cent  per  gallon.  This  includes  four  men  at  70  cts.  per  day  for 
pumping,  and  the  wear  and  tear,  interest  on  the  original  cost  of  the 
apparatus,  and  all  possible  extra  expenses.  It  would  not  cost  much  over 
1/12  of  a  cent  p^r  gallon  in  this  country,  even  if  we  had  to  buy  a  $200 
motor  (2^  H.  P.)  in  addition  to  the  apparatus  itself.  It  need  not  cost 
any  more  than  this,  for  the  motor  takes  care  of  itself  when  once  started, 
and  any  extra  horse  power  could  be  used  to  advantage  in  pumping  wine 
from  one  tank  to  another. 

In  conclusion  we  wish  to  express  the  sincere  thanks  of  the  University 
to  those  who  helped  us  with  suggestions,  money  and  material. 

Messrs.  Toulouse  and  Delorieux,  of  622  Commercial  street,  San  Fran- 
cisco, constructed  the  apparatus  according  to  our  designs,  and  it  is  due  in 
no  small  degree  to  the  extra  time  and  trouble  bestowed  by  them  upon  its 
construction  and  modifications  that  the  experiments  proved  successful. 

Mr.  D.  M.  Doub,  of  137  First  street,  San  Francisco,  came  forward  in  the 
most  public-spirited  manner,  loaning  us  several  of  the  ''blowers"  and 
"exhaust -fans''  needed.  But  for  such  liberality  the  experiments  could 
not  have  been  undertaken. 

The  Pelton  Water-wheel  Co.  also  helped  us  not  only  with  the  loan  of 
machinery,  but  also  by  making  for  us  on  the  shortest  possible  notice  such 
alterations  as  were  suddenly  found  necessary. 

Mr.  J.  Henshaw  Ward  provided  for  our  exclusive  use  at  the  Natoma 
Vineyard  $150.00  worth  of  the  best  wine  hose,  not  otherwise  obtainable. 

Mr.  J.  H.  Wheeler  and  Mr.  J.  Rennie,  the  lessees  of  the  Natoma  Vine- 
yard, allowed  us  to  use  part  of  the  vintage  and  cellar. 

To  Mr.  Wm.  Wehner  of  Evergreen  we  are  especially  indebted,  not  only 
for  the  use  of  the  cellar,  vintage,  laborers,  etc.,  but  for  the  hospitality  and 
attention  he  bestowed  upon  us.  The  kindness  and  assistance  we  received 
at  his  hands  was  exceptional. 

Descriptions  of  the  apparatus  used  abroad  are  given  alongside  of  the  form 
we  have  devised,  so  that  the  wine-maker  may  choose  between  them. 

All  that  we  desire  is  that  some  kind  of  effort  shall  be  made  to  control 
temperatures,  be  it  the  use  of  ice,  water,  air  or  anything  else ;  for  it  is  cer- 
tain that  if  the  temperature  is  controlled  there  will  be  an  improvement  of 
from  ten  to  one  hundred  percent  in  the  quality  of  Californian  wine. 

The  Viticultural  Staff  of  the  College  of  Agriculture  will  cheerfully  confer 
and  advise  with  any  persons  interested  in  this  subject,  and  assistance  in 
the  construction  or  working  of  coolers  of  any  sort  will  be  given.  WThile 
we  think  that  our  apparatus  is  better  than  any  of  the  rest,  all  that  we 
desire  is  that  there  be  some  sort  of  cooling  apparatus  used,  and  if  our  efforts 
contribute  to  the  attainment  of  this  end,  we  will  be  satisfied. 


tOUIS  ROESCH  CO.,  PRINTERS,  S.  F 


